Fine, assuming you are right, what’s the alternative ?

that’s easy, you even said it out loud:

And if the kid is educated well, he would refuse alchool from an adult that is not his parent or relatives. If not maybe you should educated your kid better than that.

now just replace alcohol with porn, and its done. just like they would drink your alcohol, they are using your internet access, its your job and responsibility to limit their access to both of these.